Method and apparatus for enabling optical communication through low intensity indicators in an appliance that uses a vacuum flourescent display

ABSTRACT

An optical interface using indicator lights is provided for an appliance having a vacuum fluorescent display (VFD) by mounting the indicator lights behind a VFD. In a VFD having a dark background, apertures are formed in the VFD so the indicator lights are enabled for optical communication through the VFD. Preferably, the apertures are formed in the dark layer covering a glass substrate in the VFD so the dark layer helps absorb reflected light that may cause optical noise in the light signals being communicated. Each aperture may be located equidistantly from a group of four pixels in the VFD.

This application cross-references U.S. Provisional Patent ApplicationSer. No. 60/351,348, filed Jan. 24, 2002, and U.S. patent applicationSer. No. 10/264,888, entitled “Appliance Control Communication Methodsand Apparatus” and filed on Oct. 4, 2002, U.S. patent application Ser.No. 10/348,305 entitled “System and Method for Communication with anAppliance Through a Light Emitting Diode” and filed on Jan. 21, 2003,and U.S. patent application Ser. No. 10/348,305 entitled “System andMethod for Communicating with an Appliance Through an Optical InterfaceUsing a Control Panel Indicator,” and filed on Jun. 24, 2003, all ofwhich are hereby expressly incorporated in their entireties byreference.

FIELD OF THE INVENTION

The present invention relates generally to optical communicationdevices, and more particularly, to optical communication devices thatuse low intensity light signals for communication.

BACKGROUND OF THE INVENTION

Appliance devices such as dishwashers, clothing washing machines,dryers, ovens, refrigerators and the like often include electricalcontrol circuits. Such control circuits receive input from the user andcontrol the operation of the appliance device based on the receivedinput. In many cases, the overall operation of the appliance ispredefined as a general matter and the user input merely modifies thepredefined operation in some way.

For example, the operation of a dishwasher typically involves theprocesses of filling, washing, draining and rinsing. Such operationsinvolve, among other things, the control of water valves, detergentvalves and motor relays. The general sequence of such operations isgenerally predefined. However, user input may be used to alter thesequence, or to define certain parameters of the sequence. For example,the user input may define whether the wash cycle is normal, light, orheavy. Although the general sequence does not necessarily changedependent upon wash cycle selection, the length of certain processeswithin the sequence does change.

A typical user input interface for a dishwasher includes a rotary knoband a plurality of pushbutton switches. The rotary knob is attached to acam that controls the sequence of operations within the dishwasher. Thecam has a number of followers that trigger the operation of the variousdishwasher components. The cam followers are positioned to cause variousoperations to be executed in a “programmed” sequence. The user selects aparticular cycle by rotating the knob to particular position associatedwith the selected cycle. Upon actuation, the cam begins to rotateautomatically started from the user selected position, performing eachoperation as defined on the cam “program” from the user-selected pointforward. The pushbutton switches are used to activate/deactivate variousoptions that are not available through the cam program. For example,pushbutton switches may be used to selectively activate a heated drycycle, a delayed start, or a high temperature wash.

More recently, electronic controllers, for example, microprocessors andmicrocontrollers, have replaced the rotary cam control device. The useof electronic controllers provides flexibility and features nottypically available in cam control devices. Moreover, as a generalmatter, replacement of moving parts, such as electromechanical rotatingcams, typically increases reliability in products.

However, the use of electronic controllers has added to the complexityof servicing appliances. Small electronic integrated circuits do notlend themselves to the methods of troubleshooting and repair that havehistorically been used with mechanical and electromechanical devices.Accordingly, malfunctions in an electronically controlled appliance aremore difficult to diagnose and resolve than those of the old, mechanicalcam controlled devices.

U. S. patent application Ser. No. 10/264,888, assigned to the assigneeof the present invention, discloses a diagnostic tool that utilizes anoptical transmitter and an optical receiver in a communication probe forbi-directional communication with an appliance controller through anindicator light of the appliance control panel and an optical detectoron an external panel of the appliance. The ability to obtain datainformation from an electronic controller may be used to obtaindiagnostic, operational, or test data from the controller regarding theoperation of the appliance.

The optical interface of the above-referenced patent applicationrequires an indicator light that is optically accessible from thesurface of the control panel of the appliance. However, a growing numberof appliances are using vacuum fluorescent displays (VFD) that do nothave indicator lights. A VFD is a display having a glass substrate towhich semiconductor circuits and phosphor pixels are mounted. Thesemiconductor circuits are used to selectively excite the pixels to formdisplays containing information regarding the operation of theappliance. Typically, a dark layer is interposed between the glasssubstrate and the phosphor pixels to provide contrast and enhance thevisibility of the displayed information.

While appliances with VFDs provide more information in a more visuallyesthetic manner than indicator lights, the light generated by a VFD maynot be adequate for optical communication with a diagnostic tool. If anindicator light is added to the control panel of an appliance having aVFD then a hole must be drilled or otherwise provided in the controlpanel. This manufacturing operation adds costs to the production of theappliance. Additionally, placement of one or more indicator lights tooperate as an optical transmitter or optical receiver outside thedisplay region occupied by a VFD may place the indicator lights in aregion of the control panel that is highly reflective. For example, manyappliances are white in color and indicator lights surrounded by a whitereflective surface may be more susceptible to optical noise arising fromreflected light. Consequently, a need exists for provision of indicatorlights to operate as optical communication devices on an appliancehaving a VFD in a manner that reduces the risk of optical noise arisingfrom reflected light.

SUMMARY OF THE INVENTION

The present invention addresses the above needs, as well as others, byproviding an optical interface for an appliance having a vacuumfluorescent display (VFD) by mounting indicator lights behind the VFDand forming apertures in the VFD so the indicator lights are opticallyaccessible through the VFD. The optical interface of the presentinvention includes a vacuum fluorescent display, a first indicator lightmounted behind the vacuum fluorescent display, and a first aperture inthe vacuum fluorescent display and aligned with the indicator light sothat the first indicator light may be operated as an opticalcommunication device for optical communication through the vacuumfluorescent display. For a VFD having a dark layer covering the glasssubstrate of the VFD, the aperture is formed in the dark layer.

Preferably, the optical interface of the present invention includes asecond indicator light mounted behind the VFD and a second aperture inthe VFD that is aligned with the second indicator light so that thesecond indicator light may be operated as an optical communicationdevice for optical communication through the VFD. Preferably, one of thefirst and the second indicator lights are operated as an opticaltransmitter and the other is operated as an optical receiver. Eachaperture is preferably located within a group of four pixels so theaperture is equidistant from each pixel within the group.

The above described features and advantages, as well as others, willbecome more readily apparent to those of ordinary skill in the art byreference to the following detailed description and accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a perspective, partially cutaway view of an exemplarydishwasher in which one or more features of the present invention may beincorporated;

FIG. 2 shows a schematic block diagram of an exemplary appliance circuitthat incorporates one or more features of the present invention;

FIG. 3 shows a flow diagram of an exemplary set of operations performedby a controller of a dishwasher in accordance with the presentinvention;

FIG. 4 shows a front view of an exemplary control panel for use inconnection with the appliance circuit of FIG. 2;

FIG. 5 shows an exploded perspective view of an exemplary control paneland circuit board that may be used in connection with the appliancecircuit of FIG. 2;

FIG. 6 shows a cross sectional view of the control panel and circuitboard of FIG. 5 assembled within a portion of a dishwasher frame;

FIGS. 7 and 8 show a schematic diagram of an exemplary control circuitwhich may be employed as the control circuit of the appliance circuit ofFIG. 2;

FIG. 9A is a schematic diagram of an exemplary indicator light circuitthat may be used to operate one indicator light as an opticaltransmitter and another indicator light as an optical receiver;

FIG. 9B is a schematic diagram of an alternative implement of an opticalreceiver using a photodetector that does not operate as an indicatorlight;

FIG. 10 shows a diagram of an exemplary vacuum fluorescent display (VFD)that may be used as a display in the dishwasher of FIG. 1;

FIG. 11 shows an exemplary arrangement in which a diagnostic tool isconfigured to communicate with a control circuit of the dishwasher ofFIG. 1 through a communication probe;

FIG. 12 shows an exploded view of the communication probe of FIG. 11;

FIG. 13 shows a flow diagram of an exemplary set of operations of thediagnostic tool of FIG. 11;

FIG. 14 shows a flow diagram of an exemplary set of operations of thecontroller of the dishwasher circuit of FIG. 2 in communication with thediagnostic tool of FIG. 11;

FIG. 15 is a block diagram of the diagnostic tool and communicationprobe of FIG. 11;

FIG. 16A is a schematic diagram of the optical receiver of thecommunication probe of FIG. 12;

FIG. 16B is a schematic diagram of the optical transmitter of FIG. 12;

FIG. 17 is a diagram of the mounting of the optical transmitter andreceiver of the communication probe of FIG. 12 in proximity to theindicator light and the photodetector of an appliance for opticalcommunication;

FIG. 18 is a diagram that depicts an optical signal exchanged betweenthe control panel of FIG. 4 and the communication probe of FIG. 12 thathas an opposite logical polarity;

FIG. 19 is a diagram that depicts an optical signal exchanged betweenthe control panel of FIG. 4 and the communication probe of FIG. 12 thathas an opposite no-data present signal but the same logical polarityaccording to another embodiment of the present invention;

FIG. 20 is a block diagram of the communication probe and a battery packcoupled to one another through a cable; and

FIG. 21 is a depiction of a battery pack directly coupled to thecommunication probe through an interconnect.

DETAILED DESCRIPTION

FIG. 1 shows an exemplary embodiment of a dishwasher 50 in which one ormore aspects of the present invention may be incorporated. Thedishwasher 50 includes a frame 51, a control panel 52, a door 53, and atub 54. The door 53 is pivotally attached to the frame 51. The door 53and frame 51 define an enclosure in which is located the tub 54. Thecontrol panel 52 is affixed to the frame 51. The enclosure formed by thedoor 53 and the frame 51 also houses control circuits and devices as isknown in the art. The exact physical arrangements of the door 53, frame51 and tub 54 are a matter of design choice. For example, the controlpanel 52 may be mounted on the door 53 in some embodiments.

FIG. 2 shows a schematic block diagram of an exemplary appliance circuit9 that incorporates one or more features of the present invention. Theappliance circuit 9 includes a control circuit 10 and a set ofelectromechanical devices. In the exemplary embodiment described herein,the electromechanical devices include a motor 16 a, a heater coil 16 b,a vent 16 c, a water valve solenoid 18 a, and a detergent releaseactuator 18 b. Such electromechanical devices are arranged within theframe and/or tub of a dishwasher such as the dishwasher 50 of FIG. 1with other mechanical devices such as pumps, rotating water sprayers,dish racks and the like as is well known in the art. The exactarrangement of the electromechanical devices and mechanical devices is amatter of design choice.

The appliance control circuit 10 controls the operation of one or moreof the electromechanical devices as to carry out one or more applianceoperations. In the exemplary embodiment described herein, the appliancecontrol circuit 10 controls the operation of the devices that cooperateto perform dishwashing operations. However, it will be appreciated thatthe principles of the present invention may readily be adapted for usein clothes washing machines, clothes dryers, as well as other appliancedevices.

The dishwasher control circuit 10 of FIG. 2 includes a switch inputcircuit 12, an optical input/output (“I/O”) circuit 14, a relay controlcircuit 16, a valve control circuit 18, a motor start circuit 20, asensor circuit 22, a controller 24, and a memory 26.

The switch input circuit 12 includes a rotating position switch 32 and aselector switch 34. In accordance with the present invention, therotating position switch 34 has a first position associated with a firstappliance function. For example, the first position may be a position inwhich a first washing cycle is selected from a plurality of possiblewashing cycles. In accordance with one aspect of the present invention,the rotating position switch 32 further includes a second positionassociated with a second appliance function, the second appliancefunction modifying the first appliance function. For example, the secondposition may select from one or more user options, such as delayedstart, a forced air drying cycle, or the like. The selector switch 34 isa switch that may be manipulated to an actuated state. The selectorswitch 34 in the actuated state is configured to generate a signalrepresentative of a selection of the first appliance function when therotating position switch is in the first position. The selector switch34 in the actuated state is further configured to generate a signalrepresentative of a selection of the second appliance function when therotating position switch is in the second position.

The rotating position switch 32 and the selector switch 34 may take avariety of forms. Exemplary embodiments of the rotating position switch32 and the selector switch 34 are described below in connection withFIG. 4. In general, however, the rotating position switch 32 includes aplurality of rotational positions in which user cycle selections may beidentified by the user or operator, and the selector switch 34 is adevice that actually causes an input signal based on the user selectionto be communicated to the controller 24.

The optical I/O circuit 14 includes at least first and second opticalcommunication devices, not shown in FIG. 2 (see, e.g., FIG. 9), that arein communication with an external surface of the appliance controlpanel. The first and second optical communication devices are operableto communicate diagnostic information between the controller 24 and anexternal device. In preferred embodiments, the optical I/O circuit 14further includes a plurality of indicator lights that communicateinformation regarding the operation of the dishwasher to the humanoperator. In accordance with one aspect of the present invention, atleast one of the optical communication devices also operates as anindicator light that communicates information to a human operator.

The relay control circuit 16 is a circuit that is configured to controlthe status of various relay contacts in accordance with control signalsreceived from the controller 24. The relays may operate to activate anddeactivate various appliance mechanisms, for example, the motor 16 a,the heater coil 16 b, and the vent fan 16 c. An exemplary relay controlcircuit 16 is shown in further detail in FIG. 8, discussed furtherbelow.

The actuator control circuit 18 is a circuit that is configured tocontrol the operation of one or more actuators in the dishwasher inaccordance with signals received from the controller 24. In theexemplary embodiment described herein, the actuator control circuit 18is configured to control the operation of a water valve solenoid 18 a,and a detergent release mechanism 18 b. Further detail regarding anexemplary embodiment of the actuator control circuit 18 is providedbelow in connection with FIG. 8.

The motor start circuit 20 is a circuit that is configured to controlthe start windings 19 b and 19 c of the motor 16 a. In accordance withone aspect of the present invention, the motor start circuit 20 includesa current sense circuit (discussed in further detail below in connectionwith FIG. 8) that is operably coupled to the run winding 19 a of theappliance motor 16 a. The current sense circuit includes a senseresistor that is formed as an etched trace in a printed circuit board.The etched trace has a geometry that defines a resistance of the senseresistor. The current sense circuit, among other things, provides amechanism by which information regarding the motor winding current maybe obtained. Such information may be used for many purposes. Forexample, the motor winding current information may be used by thecontroller 24 to determine when to activate and de-activate the startwindings 19 b and 19 c in the motor 16 a. However, as will be discussedbelow, the controller 24 may also use the information from the currentsense circuit to adjust water levels.

The sensor circuit 22 is a circuit that is configured to provide to thecontroller 24 electrical signals representative of a sensed condition ofthe dishwasher operation. For example, the sensor circuit 22 in theexemplary embodiment described herein includes a temperature sensor, asoil sensor, and a motor current sensor. Further detail regarding thesensor circuit 22 is provided below in connection with FIGS. 8 and 10.

The controller 24 is a processor-based control circuit that is operableto provide control signals to the relay control circuit 16, actuatorcontrol circuit 18, and the motor start circuit 20, responsive to inputsignals received from the switch input circuit 12 and the sensor circuit22. The controller 24 may suitably include a microprocessor, amicrocontroller, and/or other digital and analog control circuitry aswell as incidental circuitry associated therewith. The controller 24 ispreferably configured to perform operations based on programinstructions stored in the memory 26 and/or memory internal to thecontroller 24.

The memory 26 comprises one or more electronic memory devices which maysuitably include a read only memory, a random access memory (“RAM”), anelectronically erasable programmable read only memory (“EEPROM”), othertypes of memory, or a combination of any of the above. In a preferredembodiment, the memory 26 includes a programmable non-volatile memory,for example, an EEPROM. Among other things, the memory 26 stores acalibration factor associated with the current sense resistor of themotor start circuit 20.

In the general operation of the dishwasher control circuit 10, anoperator typically provides as input a first input signal representativeof a select cycle operation of the dishwasher via the switch inputcircuit 12. For example, the first input signal may be one thatcorresponds to a request for a full wash cycle. The operator may alsoprovide as a second input via the switch input circuit 12 a second inputsignal representative of an operation modification option, such as, forexample, an additional heated dry cycle, or a delayed start. Mostappliances, including dishwashers, clothes washing machine, clothesdryers and the like have commonly featured a main cycle selection thatmay be modified by one or more separate option selections.

In any event, the controller 24 receives the first input signal and, ifapplicable, the second input signal, and commences a dishwashingoperation accordingly. In a typical wash cycle, the general cycle is asfollows: 1) water fill, 2) spray water, 3) release detergent, 4) spraywater, 5) drain water, 6) water fill, 7) spray water, and 8) drainwater. It will be appreciated that the above cycle may readily bemodified or altered as is known in the art.

FIG. 3 shows a flow diagram 100 of the exemplary set of operationsperformed by the controller 24 to effectuate a normal cycle operation ofthe dishwasher. It will be appreciated that the flow diagram 100 of FIG.3 is given by way of example only, and that those of ordinary skill inthe art may readily modify the flow diagram to suit their specificimplementations. In addition, as discussed below in connection with FIG.4, the operation of the flow diagram 100 may vary based on user input ofcycle selection. Nevertheless, the flow diagram 100 illustrates thegeneral operation of typical controller 24 of a dishwasher according tothe invention.

In step 102, the controller 24 causes an initial water fill operation totake place. To this end, the controller 24 provides a signal to theactuator control circuit 18 that actuates the water valve solenoid 18 a,thereby causing the water valve to open. The controller 24 furtherprovides a signal to the relay control circuit 16 that energizes theheater coil 16 b. The controller 24 then allows the water to fill for apredetermined amount of time. It is noted that the water pressure may bekept constant by a pressure sensitive valve, as is known in the art.Thus, the controller 24 effectively controls water the water levelcontrolling the amount of time that the near constant flow of water isprovided to the tub 54. The controller 24 also monitors, using sensorsignals from the sensor circuit 22, the water temperature.

When the water level is adequate, then the controller 24 provides asignal to the actuator control circuit 18 that de-energizes the watervalve solenoid 18 a, thereby causing the water valve to close. When thewater temperature is adequate, then the controller 24 provides a signalto the relay control circuit 16 that de-energizes the heater coil 16 b.

In step 104, the controller causes a spray operation to occur. The sprayoperation is one in which the heated water within the dishwasher tub 54is sprayed throughout the tub 54 onto the items to be cleaned. In step104, the spray operation serves as a pre-rinse cycle. However, ifdetergent is placed loosely in the tub, then the spray operation of step104 rinses and cleans simultaneously. To effectuate the spray cycle, thecontroller 24 provides a signal to the relay control circuit 16 thatcauses the run winding 19 a of the motor 16 a to be energized. The motor16 a drives the pump, not shown, that causes the water to be sprayedthroughout the tub 54.

The controller 24 further provides a signal to the motor start circuit20 that causes one of the start windings 19 b or 19 c to be energized.As is known in the art, it is advantageous to employ a separate startwinding to bring a motor up to speed, and then de-energize the startwinding once the motor reaches operating speed. Thereafter, only the runwinding is energized during steady-state operation of the motor. Thus,the controller 24 provides a signal to the motor start circuit 20 thatcauses the start winding to be de-energized when the motor 16 a reachessteady state. The controller 24 monitors the current using the currentsense circuit (described above in connection with FIG. 2) to determinewhen the motor 16 a is in steady-state.

In step 106, which occurs a predetermined time period after the start ofstep 104, the controller 24 causes additional detergent to be released.As is known in the art, a separate detergent receptacle is disposedwithin the dishwasher that is released after the spraying cycle hasbegun. In the exemplary embodiment described herein, the controller 24causes the release of additional detergent by providing a signal to theactuator control circuit 18 that causes a detergent release mechanism toopen. It will be appreciated, however, that additional detergent may bereleased using purely mechanical means. It will further be appreciatedthat in some embodiments, step 106 may be preceded by separate drain,fill, and spray steps to remove the dirty water generated in theoriginal spray step 104 from the tub 54.

Regardless of whether the water is exchanged prior to releasingdetergent in step 106, the controller 24 continues the spray operationin step 108 to spray the water with the newly released detergent ontothe items to be cleaned. The spray operation may suitably occurcontinuously from step 104 through step 108. In such a case, thecontroller 24 need not change the state of the motor relay or the motorstart control circuit 20.

After a predetermined amount of time in steps 104 through 108, or atleast step 108, the controller 24 proceeds to step 110 in which water isdrained from the tub 54. To this end, the controller 24 provides asignal to the relay circuit 16 that opens the relay to de-energize themotor 16 a. In the exemplary embodiment described herein, the controller24 thereafter provides signals to the relay circuit 16 and the motorstart circuit 20 that cause the pump motor 16 a to rotate in a reversedirection. In the exemplary embodiment described herein, the reverserotation of the motor causes the pump to operate in pumping water out ofthe tub 54, as is known in the art. However, in other embodiments, aseparate motor and/or pump may be used to empty the tub 54. In anyevent, when a low water level is detected by the controller 24 throughthe sensor circuit 22, then the controller 24 causes the motor 16 a tobe de-energized. In the embodiment described herein, the low water levelmay suitably be detected using the motor run winding current sensed bythe current sensor.

Steps 112 through 116 represent the rinse cycle of the dishwashingoperation. In step 112, the controller 24 performs a water filloperation similar to that described above in connection with step 102.Thereafter, in step 114, the controller 24 performs the spray operation,similar to that of step 104. If a so-called rinse-aid receptacle isemployed, the controller 24 may in step 114 provide a signal to therelay control device 16 that causes a rinse-aid release mechanism toopen. In any event, after a predetermined duration of spraying in step114, the controller 24 proceeds to step 116 to drain the water from thetub 54. To this end, step 116 may suitably be substantially the same asstep 110.

As discussed above, the operations of the flow diagram 100 may varysomewhat from dishwasher to dishwasher. Moreover, within any particulardishwasher, the operations of the flow diagram 100 may be alteredthrough user selection of particular cycles and options. However,regardless of variation in such operations, any appliance may readilyobtain the benefits of the novel switch arrangement of the presentinvention by incorporating the rotating switch and selection switch inan environment in which the user is allowed to provide input thataffects dishwasher operation.

In addition, the benefits of the current sense circuit of the presentinvention may be obtained by incorporating the sense resistor of thepresent invention in any appliance that employs current feedback tocontrol the operation of the motor or some other device. Moreover, thebenefits of external communication of one aspect of the presentinvention may be obtained by incorporating the first and second opticalcommunication devices of the present invention in any householdappliance that incorporates an electronic controller capable ofeffecting data communication. Indeed, a dishwasher or other appliancewill be enhanced by incorporation of any of the above described benefitsindividually or in combination.

FIG. 4 shows a front view of an exemplary control panel 52 for use inconnection with the dishwasher control circuit 10 of FIG. 2. The controlpanel 52 is preferably located at a user-accessible portion of thedishwasher apparatus. The control panel 52 provides the interfacethrough which an operator generates control input signals and throughwhich information related to the operation of the dishwasher may becommunicated to the user. To this end, the control panel 52 includes anexemplary embodiment of the rotating position switch 32, an exemplaryembodiment of the selection switch 34, and a plurality of indicatorlights 36 a through 36 i.

As discussed above, the rotating position switch 32 and the selectionswitch 34 constitute a portion of the switch input circuit 12 of FIG. 2.The rotating position switch 32 is rotatably mounted to the dishwasherin a manner described in further detail below in connection with FIGS. 5and 6. The rotating position switch 32 includes a position indicator 35that defines a reference point for the annular (i.e. rotational)position of the rotating position switch 32.

Disposed around the rotating position switch 32 at distinct annularpositions are cycle selection indicia 38 a through 38 f and optionchoice indicia 40 a through 40 d. Each of the indicator lights 36 athrough 36 d is disposed adjacent to corresponding option choice indicia40 a through 40 d.

As shown in FIG. 4, the exemplary cycle choice indicia include“Cancel/Drain” indicia 38 a, “Rinse Only” indicia 38 b, “Light Wash”indicia 38 c, “Medium Wash” indicia 38 d, “Heavy Wash” indicia 38 e and“Pots/Pan” indicia 38 f. Such indicia represent the available cycleselections. The operator or user selects a cycle by rotating therotating position switch 32 until the position indicator 35 is alignedadjacent to the indicia 38 x that corresponds to the type of washingcycle desired, where x is any of a through f. In the exemplaryembodiment described herein, the operator further actuates the selectorswitch 34 to input the cycle selection to the controller 24.

In general, the user cycle selections associated with the indicia 38 athrough 38 f are carried out by altering or adjusting the operations ofthe flow diagram 100 of FIG. 3. For example, selection of the “HeavyWash”, “Medium Wash” and “Light Wash” may vary the length of step 104and/or step 108. In another example, the selection of “Rinse Only” mayomit steps 102 through 110 entirely. The selection of “Drain/Cancel”causes immediate execution of step 116. It will be appreciated that thepresent invention is in no way limited to any particular number or typeof cycle choices that are available to the operator. Nor is the presentinvention limited to the cycle choices and how those choices areimplemented by the controller 24. Moreover, other appliances such asclothes washers and dryers will necessarily have a different set ofcycle choices.

After selecting a cycle choice as described above, the operator maysubsequently select an optional operation by rotating the rotatingposition switch 32 until the position indicator 35 is aligned adjacentto the option choice indicia 40 x that corresponds to the optiondesired, where x is any of a through d. As shown in FIG. 4, theexemplary option choice indicia include “Hi-Temp Wash” indicia 40 a,“Air Dry” indicia 40 b, “2 Hour Delay” indicia 40 c, and “4 Hour Delay”indicia 40 d. In the exemplary embodiment described herein, the operatorfurther actuates the selector switch 34 to input the cycle selection tothe controller 24.

In general, the user option selections associated with the indicia 40 athrough 40 d are carried out by the controller 24 in self-evident ways.For example, selection of the “Hi-Temp Wash” option could cause thecontroller 24 to adjust the temperature threshold at which it causes theheating coil 16 b to be de-energized in step 102 of FIG. 3. In anotherexample, selection of “Air Dry” causes the controller 24 to energize thevent 16 c and/or the heating coil 16 b after completion of step 116 ofFIG. 3. The vent 16 c and heating coil 16 b help dry items located inthe tub 54 after the water is drained out in step 116. The selection of“2 Hour Delay” and “4 Hour Delay” causes the controller 24 to delay thecommencement of the operations identified in the flow diagram 100 ofFIG. 3 until the corresponding delay has occurred. It will beappreciated that the exact option choices provided to the operator, andhow those options are implemented by the controller 24, are largely amatter of design choice. Moreover, other types of appliances willnecessarily have a different set of option choices.

Each of the indicator lights 36 e through 36 i is disposed adjacent tocorresponding cycle status indicia 42 a through 42 e. The cycle statusindicia include “Clean” 42 a, “Wash” 42 b, “Heat Water” 42 c, “Rinse” 42d, and “Drying” 42 e. In operation, the controller 24 energizes theindicator light 36 e adjacent to the “Clean” indicia 42 a uponcompletion of step 116 of FIG. 3. The controller 24 energizes the “Wash”indicia 42 b during steps 104-110 of FIG. 3. The controller 24 energizesthe “Heat Water” indicia 42 c during steps 102 and 112 of FIG. 3. Thecontroller 24 energizes the “Rinse” indicia 42 d during steps 114 and116 of FIG. 3. The controller 24 energizes the “Drying” indicia 42 eduring the optional air dry operation, discussed above.

FIGS. 5 and 6 show in further detail an exemplary mechanicalconfiguration of the control panel 52 and the control circuit 10 into aportion of the dishwasher frame 51. FIG. 5 shows an exploded view of thecontrol panel 52 apart from the dishwasher frame 51. FIG. 6 shows afragmentary cross-section of the dishwasher frame 51 with the controlpanel 52 installed therein.

Referring to FIGS. 5 and 6 contemporaneously, the control panel 52includes a primary printed circuit board (“PCB”) 62, a secondary PCB 64,a dual switch assembly 66, and housing 68. The primary PCB 62 and thesecondary PCB 64 contain the control circuit 10 (see FIG. 2). The dualswitch assembly 66 includes components of both the selector switch 34and the rotating position switch 32. The rotating position switch 32includes a rotatable handle 70, a rotating shaft 72, a tactile feedbackmember 73, a conductive cam 74, and a spacer 76. The selector switch 34includes a pushbutton 78, an axial displacement shaft 80, and anelastomeric spring contact member 82. The primary PCB 62 furtherincludes first and second selector contacts 84 and 86, respectively,annular position contacts 88 a through 88 j, and an annular continuouscontact 89.

The rotatable handle 70 comprises a substantially circular outer ring120 and a substantially circular inner ring 122. A disk-like bottomsurface 123 extends from the bottom edge of the inner ring 122 to thebottom edge of the outer ring 120. Two radial members 124 and 126 extendaxially upward from the bottom surface 123 and extend radially inopposite directions from the inner ring 122 to the outer ring 120. Theposition indicator 35 (see also FIG. 4) is disposed on the radial member124. Within the inner ring 122 is a detent 128 that chords off a portionof the inner ring 122. The rotatable handle 70 is disposed above a firstside 90 of the housing 68.

The rotating shaft 72 includes an elongate shaft 130, a top ring 132, atooth ring 134, a base 136, and a hollow interior 137. The hollowinterior 137 extends axially along the entire length of the rotatingshaft 72. The top ring 132 has diameter configured to fit within theinner ring 122 of the rotatable handle 70. To this end, the top ring 132includes a chorded outer surface region 138 configured to allow the topring 132 to fit within the portion of the inner ring 122 that includesthe detent 128. The top ring 132 is also, except for the chorded region138, preferably slightly frustoconical in shape, tapering slightlyinward from bottom to top. (See FIG. 6).

The elongate shaft 130 extends axially downward from the top ring 132and has a diameter that is less than the inner diameter of the innerring 122. The tooth ring 134 is disposed axially below the elongateshaft and has a radius generally exceeding that of the elongate shaft130 and the inner ring 122. The tooth ring 134 includes a plurality ofteeth 135 formed by slight radial concavities disposed at annularpositions corresponding to the rotational contacts 88 a through 88 i. Inparticular, each pair of adjacent teeth 135 is separated by a concavity.

The base 136 includes a first hollow ring 136 a and a second hollow ring136 b. The first hollow ring 136 a is disposed directly below the toothring 134 and has an outer radius slightly exceeding the radius of thetooth ring 134. The second hollow ring 136 b is disposed directly belowthe first hollow ring 136 a and has an outer radius exceeding that ofthe first hollow ring 136 a.

In general, the elongate shaft 130 extends through an opening 94 in thehousing 68 such that the top ring 132 (and rotatable handle 70) is (are)located above the first surface 90 of the housing 68 and the tooth ring134 and base 136 are located below a second surface 92 of the housing68.

The tactile feedback member 73 includes an open rectangular frame 138having length and width dimensions generally exceeding the radius of thetooth ring 134 but generally less than the second hollow ring 136 b ofthe base 136. Disposed on two inner edges of the frame 138 are detents140. The detents 140 have dimensions configured such that each may bereceived by any of the concavities between the teeth 135 of the toothring 134. The frame 138 is generally disposed around the tooth ring 134,trapped in an axial position between the second surface 92 of thehousing 68 and the base 136. The frame 138 is preferably at least inpart elastically deformable such that manual rotational force applied tothe rotating shaft 72 causes the teeth 135 to overcome and traverse thedetents 140.

The conductive cam 74 includes an anchor 142, a first cam contact 144and a second cam contact 146. The anchor 142 is secured to the base 136of the rotating shaft 72, and more particularly, within the secondhollow ring 136 b of the base 136. The first cam contact 144 extends ina tangential direction (with respect to the rotating elements ofrotating shaft 72) from the anchor 142, and is also slightly inclined toextend axially downward from the base 142. The first cam contact 144 isdisposed at a radial position aligned with the radial position of therotational position contacts 88 a through 88 j of the primary PCB 62.The second cam contact 146 is disposed radially spaced apart from thefirst cam contact 144 but otherwise extends from the anchor 142 in asimilar manner. The second cam contact 144 is disposed at a radialposition aligned with the radial position of the continuous contact 89of the primary PCB 62.

The spacer 76 includes an arched ring structure 148 that arches axiallydownward moving radially outward from the inner edge of the ringstructure 148. Thus, the ring structure 148 extends from a substantiallyflat, radially extending surface near its inner edge, to a substantiallyvertical, axially extending surface near its outer edge. The spacer 76further includes a plurality of axially extending legs 150, each havinga respective retention barb 152 disposed thereon. The plurality of legs150 are received by corresponding holes 154 in the primary PCB 62 andare retained within the holes 154 by engagement of the retention barbs152 against the opposite surface of the PCB 62. The ring structure 148has an outer diameter that is configured to fit within the first hollowring 136 a as shown in FIG. 6.

The pushbutton 78 is in the general shape of a cap that is slidablyreceived into the inner ring 122 of the rotatable handle 70. Thepushbutton is 78 secured to the axial displacement shaft 80. Thepushbutton 78 has an outer radius that exceeds an inner radius of thetop ring 132 of the rotating shaft 72, thereby defining the axial limitof downward travel of the pushbutton 78.

The elastomeric spring contact member 82 includes a base ring 156, afrustoconical spring portion 158, and a contact/button member 160. Thebase ring 156 has a radius configured to fit within and be trapped bythe arched ring structure 148, as shown in FIG. 6. The frustoconicalspring portion 158 extends radially inward and axially upward from thebase ring 156 and terminates in the contact/button member 160. Thecontact button member 160 extends axially outward from, but is disposedradially within, the arched ring structure 148. The contact/buttonmember 160 includes a conductive contact such as carbon or the like, notshown, on its underside, which is configured to contact the first andsecond conductive contacts 84 and 86 when the spring contact member 82is in a compressed or actuated state. In an alternative embodiment, thespring contact member may be formed of a conductive metal or anothertype of nonconductive material that includes conductive contacts.

The axial displacement shaft 80 includes an elongate member 162 and abottom flange 164. The axial displacement shaft 80 extends in anelongate manner from the pushbutton 78 to the contact button member 160.To this end, the elongate member 162 is slidably disposed within thehollow interior 137 of the rotating shaft 72. The bottom flange 164 hasa radius exceeding that of the hollow interior 137, thereby limiting theaxially upward movement of the axial displacement shaft 80.

The dual switch assembly 66 effectively permits two basic operations,rotational movement of the rotating position switch 32 to allow the userto align the position indicator 35 with a select cycle choice or optionchoice (See FIG. 4), and actuation of the selector switch 34 to “enter”the selected cycle or option choice into the controller 24 of thecontrol circuit 10.

An operator performs rotational movement by grasping the rotatablehandle 70 and applying rotational force. The rotational force of thehandle 70 translates to the rotating shaft 72 through the engagement ofthe detent 128 of the rotatable handle 70 with the chorded region 138 ofthe rotating shaft 72. The rotational movement of the rotating shaft 72causes the teeth 135 to traverse the detents 140 of the tactile feedbackmember 73. In particular, the rotational force causes the teeth 135adjacent to the detents 140 to push against the detents 140. The forceagainst the detents 140 is relieved through outward flexing of therectangular frame 138. As each of the teeth 135 passes the detents 140,the elastic nature of the rectangular frame 138 causes the rectangularframe to “snap” back, such that the detents 140 are received into thenext concavity (between the teeth 135) of the tooth ring 134. Thisflexing and snapping as the teeth 135 rotate past the detents 140provide tactile and preferably audible feedback to the user, and furtherassist the user in aligning the rotating position switch 32 intodiscrete annular positions that correspond to the contacts 88 a through88 j. It is noted that rotational movement of the rotating shaft 72 alsorotates the cam contact 74.

When the user aligns the position indicator 35 with the indiciaassociated with the desired cycle or option choice (See FIG. 4), thenthe user stops applying rotational force. When the rotational force isremoved, the tactile feedback member 73 further perfects the alignmentof the rotating position switch 32 through the operation of the elasticproperties described above. In the final annular position, the first camcontact 144 is in direct electrical contact with the contact 88 x,wherein x is one of a through j, that corresponds to the user'sselection. In all positions, the second cam contact 146 is in directelectrical contact with the continuous contact 89. Because the first camcontact 144, the second cam contact 146, and the anchor 142 form acontinuous conductor, the conductive cam 74 electrically connects thecontact 88 x to the continuous conductor 89. As will be discussed below,such connection creates a unique signal that is recognized by thecontroller 24 as corresponding to the user's selection.

Thus, rotation of the rotating position switch 32 to one of its annularpositions effectively creates a unique signal recognized by thecontroller 24 that is indicative of a user selection. The controller 24may then perform operations corresponding to the user selection based onthe recognition of the unique signal associated with the contact 88 x.

However, in accordance with one aspect of the present invention, theunique signal that conveys the user cycle selection information to thecontroller 24 is not recognized or acted upon until the selector switch34 is actuated. Thus, merely aligning the rotating position switch 32with a desired cycle or option selection will not necessarily cause thecontroller 24 to carry out the desired operations. The selection must be“entered” by actuating the selector switch 34.

To actuate the selector switch 34 in the embodiment described herein,the user depresses the pushbutton 78, thereby causing axial movementthereof. Axial movement of the pushbutton 78 causes like axial movementof the axial displacement shaft 80. The axial movement of the axialdisplacement shaft 80 in turn applies axial force to the contact/button160. The axial force of the contact/button 160 causes the frustoconicalspring portion 158 to elastically compress, thereby allowing downwardaxial movement of the contact/button 160 to the first and secondconductive contacts 84 and 86. The conductor on the underside of thecontact/button 160 electrically connects the contacts 84 and 86. Whenthe contacts 84 and 86 are connected, a signal is provided to thecontroller 24 that causes the controller 24 to receive, recognize, orprocess the unique signal created by the electrical connection betweenthe select contact 88 x with the continuous contact 89 by the rotatingposition switch. The controller 24 thereafter performs operations basedon the user selection as described above in connection with FIGS. 3 and4.

FIGS. 7, 8 and 9 show collectively a schematic diagram of an exemplaryembodiment of the control circuit 10 of FIG. 2. FIG. 7 shows a portionof a schematic diagram of an exemplary embodiment of the control circuit10 of FIG. 2 that includes the controller 24 and elements of the dualswitch assembly 66 of FIGS. 5 and 6. FIG. 8 shows a portion of thecontrol circuit 10 that includes the relay control circuit 16, theactuator control circuit 18 and the sensor circuit 22. FIG. 9 shows theoptical I/O circuit 14.

Referring to FIG. 7, the controller 24 in the exemplary embodiment ofFIG. 7 includes a microcontroller U1 that is operable to receive scaledanalog inputs as well as receive and generate digital signals. Suchdevices are known in the art. In the exemplary embodiment describedherein, the microcontroller U1 is the commercially available SG ThomsonST72324K. Supporting circuitry for the microcontroller U1 include acrystal oscillator circuit 202. It will be appreciated that thecontroller 24 could alternatively take other forms, such as amicroprocessor having one or more analog-to-digital converters connectedthereto for the receipt of analog signals. An EEPROM U5 is seriallyconnected to the microcontroller U1 and is configured to storecalibration information, diagnostic data, and other data as necessary.

The switch input circuit 12 in the embodiment of FIG. 7 includes aplurality of series connected resistors R4, R5, R7, R9, R11, R12, R13,R14, R16 and R17, the contacts 88 a through 88 j, the conductive cam 74,the continuous contact 89, a filter capacitor C2, a filter resistor R19,contacts 84 and 86, and button/contact 160.

The resistors R4, R5, R7, R9, R11, R12, R13, R14, R16 and R17 are seriesconnected between ground and a bias voltage −VC. The contact 88 a iselectrically connected between the resistor R4 and ground. Each of theremaining contacts 88 b through 88 j are connected between adjacentpairs of the resistors R4, R5, R7, R9, R11, R12, R13, R14, R16 and R17.The continuous contact 89 is electrically connected through the filterformed by the capacitor C2 and resistor R19 to the contact 86. Thecontact 84 is coupled to ground.

From the above description, those of ordinary skill in the art willrecognize that the resistors R4, R5, R7, R9, R11, R12, R13, R14, R16 andR17 form a ten stage voltage divider or voltage ladder. As a result,each of the contacts 88 a through 88 j carries a unique voltage leveldefined by its position on the voltage ladder. In the exemplaryembodiment described herein, the resistors R4, R5, R7, R9, R11, R12,R13, R14, R16 and R17 all have the same resistance value. As a result,the voltage drop across each of the resistors R4, R5, R7, R9, R11, R12,R13, R14, R16 and R17 is the same. For example, if the voltage −VC isequal to −10 volts, then the voltage drop across each of the resistorsR4, R5, R7, R9, R11, R12, R13, R14, R16 and R17 would be 1 volt. In suchan example the resulting voltage levels at each of the contacts 88 athrough 88 j would be as set forth below in Table 1: TABLE 1 ContactVoltage 88a  0 V 88b −1 V 88c −2 V 88d −3 V 88e −4 V 88f −5 V 88g −6 V88h −7 V 88i −8 V 88j −9 V

As discussed above in connection with FIGS. 5 and 6, the conductive cam74 is operable to selectively couple the continuous contact 89 with anyof the contacts 88 a through 88 j. In FIG. 7, the conductive cam 74 isshown in an exemplary position connecting the continuous contact 89 withthe contact 88 c. As a result, the voltage on the continuous contact 89is equal to the voltage at the contact 88 c. This voltage propagates tothe microcontroller U1 through the SWITCHIN input, which is coupledbetween the resistor R19 and the contact 86.

As discussed above, the microcontroller U1 does not automatically actupon the voltage from the continuous contact 89. Instead, themicrocontroller U1 must receive a trigger signal via the selector switch34 before responding to the voltage level on the continuous contact 89.To this end, when the button/contact 160 is actuated and thus contacts84 and 86 are electrically connected, then the microcontroller inputSWITCHIN is shorted to −VC. The microcontroller U1 is configured torecognize the −VC voltage as a trigger to receive input based on theposition of the conductive cam 74.

In particular, in accordance with the example illustrated in FIG. 7,when the button/contact 160 is in its normally open position(un-actuated), the voltage at SWITCHIN is equal to the voltage at thecontact 88 c. The microcontroller U1 does not, however, perform actionsresponsive to the voltage at SWITCHIN. Thus, movement of the rotatingposition switch 32 and the resulting movement of the conductive cam 74to another contact 88 x will change the voltage at SWITCHIN but will notalter operations of the microcontroller U1.

However, if the microcontroller U1 detects −VC at SWITCHIN, then it willwait until the −VC voltage is removed from SWITCHIN, read the steadystate voltage at SWITCHIN, and then perform a set of operations based onthe steady state voltage. Thus, when the selector switch 34 is actuated,the microcontroller U1 detects −VC at SWITCHIN and then waits for thesubsequent voltage. As the selector switch 34 is released, −VC is nolonger connected to SWITCHIN. Instead, the voltage from the contact 88 xat which the conductive cam 74 is positioned returns to SWITCHIN. Thevoltage from the contact 88 x thus constitutes the subsequent voltagedetected by the microcontroller U1. The microcontroller U1 then performsoperations associated with the user cycle or option selection thatcorresponds with the position of the contact 88 x.

In summary, as discussed above in connection with FIGS. 5 and 6, theuser selection is communicated via the annular position of the rotatingposition switch 32 through the annular positioning of the contacts 88 athrough 88 j. The contacts 88 a through 88 j each provide a uniquevoltage level to the microcontroller U1 because they are connected todiscrete positions of a multi-stage voltage ladder circuit. Thus, thevoltage level detected by the microcontroller U1 corresponds uniquely toan annular position selected by the user.

In addition, the microcontroller U1 only reads the ladder voltage uponreceipt of a unique activation signal, the voltage level −VC, whichresults from the actuation of the selector switch 34.

It will be appreciated that other electrical circuits may readily beemployed to convey position information to the microcontroller U1. Forexample, the discrete contacts 88 a through 88 j may be replaced with asingle rheostat that also forms a voltage divider that provides avoltage level to the microcontroller based on annular position. In stillanother embodiment, each position contact 88 a through 88 j may simplybe connected to a different input of the microcontroller U1, or to amultiplexor that provides a four digit binary code to themicrocontroller U1. While these and other alternatives are viable andstill obtain many of the benefits of the present invention, theembodiment disclosed herein provides additional advantages because itrequires minimal inputs to the microcontroller U1 and it can achievemore reliable input value separation than typical rheostats. Onealternative that only requires one additional microcontroller input isan alternative in which the contacts 84 and 86 provide a signal to aseparate microcontroller input, as opposed to the same input to whichthe ladder voltage is provided.

FIG. 8 shows an exemplary schematic of the portion of the controlcircuit 10 that includes the relay control circuit 16, the actuatorcontrol circuit 18, the motor start circuit 20, and the sensor circuit22. The relay control circuit 16 includes a motor relay K1, a heaterrelay K2, and a vent relay K3. The motor relay K1 includes a coil 204and a set of contacts 206, the heater relay K2 includes a coil 208 and aset of contacts 210, and the vent relay K3 includes a coil 212 and a setof contacts 214. The motor relay contacts 206 are operably coupled toselectively and controllably complete the circuit through the runwinding 19 a of the motor. (See FIG. 2). The heater relay contacts 210are operably coupled to selectively and controllably complete thecircuit through the heater coil 16 b. (See FIG. 2). The vent relaycontacts 214 are operably coupled to selectively and controllablycomplete the circuit through the vent 16 c. (See FIG. 2).

The motor relay coil 204 is operably coupled to a MTR COMMON output ofthe microcontroller U1 (see also FIG. 7) through a pair of drivertransistors Q6 and Q11. The heater relay coil 208 is operably coupled toa HEATER output of the microcontroller U1 (see also FIG. 7) through apair of driver transistors Q5 and Q1O. The vent relay coil 212 isoperably coupled to a VENT output of the microcontroller U1 (see alsoFIG. 7) through a pair of driver transistors Q7 and Q8.

Accordingly, when during the operations of the dishwasher (see FIGS. 3and 4) the microcontroller U1 is required to turn on the motor 16 a, themicrocontroller U1 provides an activation signal to its MTR COMMONoutput. The activation signal is amplified through the driver resistorsQ6 and Q11. The amplified activation signal energizes the motor relaycoil 204, thereby causing the motor relay contacts 206 to close. Closureof the motor relay contacts 206 allows motor drive current to flowthrough the run winding 19 a of the motor 16 a. However, when the motor16 a first begins to run, one of the start windings 19 b or 19 c mayalso be energized as will be discussed further below in connection withthe motor start circuit 20.

Similarly, when during the operations of the dishwasher (see FIGS. 2 and3) the microcontroller U1 is required to energize the heater coil 16 b,the microcontroller U1 provides an activation signal to its HEATERoutput. The activation signal is amplified through the driver resistorsQ5 and Q10. The amplified activation signal energizes the heater relaycoil 208, thereby causing the heater relay contacts 210 to close.Closure of the heater relay contacts 210 allows current to flow throughthe heater coil 16 b, thereby generating heat.

Likewise, when during the operations of the dishwasher (see FIGS. 2 and3) the microcontroller U1 is required to energize the vent 16 c, themicrocontroller U1 provides an activation signal to its VENT output. Inthe exemplary embodiment described herein, the vent 16 c may be usedduring execution of the optional “Air Dry” operation after step 116 ofFIG. 3. In any event, the vent activation signal is amplified throughthe driver resistors Q7 and Q8. The amplified activation signalenergizes the vent relay coil 212, thereby causing the vent relaycontacts 214 to close. Closure of the vent relay contacts 214 closes thepower circuit through the vent 16 c, thereby activating the vent 16 c.

The sensor circuit 22 includes a soil sensor 216, a temperature sensor218, and a current sensor 220. The soil sensor 216 is coupled to theSOIL SENSOR input of the microcontroller U1 through a conditioningcircuit 222. The temperature sensor 218 is coupled the TEMP input of themicrocontroller U1 through a conditioning circuit 224. The currentsensor 220 is coupled to the ISENSE input of the microcontroller U1through a conditioning circuit 226.

In general, the soil sensor 216 and the corresponding conditioningcircuit 222 cooperate to generate a signal that has a qualityrepresentative of a soil level which is recognizable to themicrocontroller U1. The microcontroller U1 may employ the soil sensorsignals from the soil sensor 216 to alter the duration of the spraysteps (e.g., steps 104-108 of FIG. 3), or to cause a repetition of oneor more steps of the wash cycle.

The temperature sensor 218 and the corresponding conditioning circuit224 cooperate to generate a signal that has a quality representative ofthe water temperature which is recognizable to the microcontroller U1.The microcontroller U1 controls the operation of the heater relay K2based on the water temperature signal.

The current sensor 220 and the corresponding conditioning circuit 226cooperate to generate a signal that has a quality representative of acurrent level in the run winding 19 a of the motor 16 a. In accordancewith one aspect of the present invention, the microcontroller U1 usesthe current level in the run winding 19 a of the motor 16 a to determinewhether or not to energize or de-energize one or more start windings 19b and/or 19 c in the motor. As is known in the art, it is advantageousto energize an additional start winding in a motor when starting themotor. After the motor achieves its steady state speed, the additionalstart winding need no longer be energized.

To this end, the microcontroller U1 processes the current sense signalsreceived at its ISENSE input and controllably energizes or de-energizesone of two start windings of the motor 16 a. Referring to the motorstart circuit 20 and FIG. 7, the microcontroller U1 includes a CCWoutput and a CW output that are coupled to the motor start circuit 20.The CCW output is coupled through a driver transistor Q230 to thecontrol input of a triac switch Q231. The triac switch Q231 is operablycoupled to controllably connect and disconnect the circuit through thecounterclockwise winding 19 c of the motor 16 a. (See FIG. 2). To thisend, one side of the triac switch Q231 is coupled to the motor neutralline, and the other is configured to be coupled to the counterclockwisewinding 19 c. (See FIG. 2). In an analogous manner, the CW output iscoupled through a driver transistor Q240 to a triac switch Q241. Oneside of the triac switch Q241 is coupled to the motor neutral line andthe other side is configured to be coupled to the clockwise winding 19 bof the motor 16 a. (See FIG. 2).

Referring again generally to the sensor circuit 22, the current sensor220 in the exemplary embodiment described herein is a relatively lowresistance shunt resistor. In the embodiment of FIG. 7, the shuntresistor 220 has a resistance value of about 0.045 ohms. In accordancewith one aspect of the present invention, the shunt resistor 220 isformed as an etched path on the primary PCB 62.

In particular, FIG. 10 shows an exemplary trace layout of the PCB 62.FIG. 10 shows the primary PCB 62 in its unpopulated state. Whenpopulated, the various elements illustrated in FIGS. 7 and 8 of thecontrol circuit 10 are mounted on the primary PCB 62. The traces on theprimary PCB 62 connect the various elements mounted on the PCB 62.

As indicated above, however, the current sensor 220 is not a separatedevice that is mounted on the primary PCB 62, but instead is formed byone of the traces. For example, in FIG. 10, the current sensor 220 is atrace 221 having a geometry, primarily its length and width, configuredto create a resistance of about 0.045 ohms. The width must be sufficientto carry the current of the run winding 19 a of the motor 16 a. In theembodiment described herein, the trace of the current sensor 220includes a plurality of switch backs 221 a in order to obtain thedesired length within a confined area of the circuit board surface.However, it will be appreciated that other trace geometries may be usedand still obtain many of the benefits of the present invention. FIG. 10further shows traces that constitute the switch contacts 88 a through 88j as well as contact 89.

The incorporation of the current sensor 220 as a trace on the PCB 62helps reduce overall cost. Prior art current sensing resistors having aresistance of less than one ohm often have consisted of coiled wiresthat were costly to both manufacture and assemble onto the circuitboard. The use of the trace as the current sensor 220 incurs relativelylittle cost, and conductive traces are well-suited for small resistancevalues.

Referring again to FIG. 8, the current sensor 220 is adapted to becoupled to a measurement point 228, which in turn is adapted to becoupled to the run winding of the motor. The current sensor 220 iscoupled on the other side to motor neutral. As a result, the currentsensor 220 represents a very low resistive path from the run winding toground, thereby forming the shunt. The ISENSE input of themicrocontroller U1 is then coupled to the measurement point 228 throughseries resistors R32 (10 k-ohms) and R220 (10 k-ohms). A biasingresistor R33 (59 k-ohms) and a protection diode D221 are coupled betweenthe junction of the two resistors R32 and R220 and a bias voltage. Acapacitor C220 (0.01 microfarads) is coupled between the junction of thetwo resistors R32 and R220 and ground.

In general, the current flowing through the run winding 19 a of themotor 16 a is shunted to ground almost entirely through the currentsensor 220 because any other path runs through the much more resistiveresistor R220. However, it is noted that an alternative path through adiode D220 is provided should the current sensor 220 become opencircuited. Nevertheless, under normal circumstances, the voltagemeasured at the reference point 228 divided by the resistance of thecurrent sensor 220 provides an approximation of the run winding current.The voltage signal at the reference point 228 is provided to the ISENSEinput through the conditioning circuit 226 formed by the resistors R32,R220, R33, diodes D221, D220 and the capacitor C220. Thus, the voltagesignal at the ISENSE input is representative of the current flowing inthe run winding 19 a of the motor 16 a. Configured as described above,the signal at the ISENSE input has a waveform that tracks the waveformof the run winding current waveform.

The microcontroller U1 may then use that ISENSE signal waveform tocontrol various aspects of the dishwasher. As discussed below, themicrocontroller U1 determines whether and when to energize andde-energize the start winding 19 b or 19 c of the motor 16 a based onthe magnitude of the run winding current. In general, when the motor 16a starts, the run winding current tends to be relatively high. As aresult, the ISENSE signal will likewise have a relatively highmagnitude. The microcontroller U1 is programmed to cause the startwinding 19 b or 19 c to be energized when the ISENSE signal has arelatively high magnitude. After the motor 16 a reaches its runningspeed, the current through the run winding 19 a drops. Accordingly, themicrocontroller U1 causes the start winding 19 b or 19 c to bede-energized when the magnitude of the ISENSE signal falls below acertain threshold.

In addition, the microcontroller U1 may determine whether to open thewater valve to adjust the water level in the tub 54 based at least inpart on the phase of the run winding current, which may also be detectedfrom the ISENSE signal waveform.

Referring specifically to the control of the start windings, anexemplary operation in which the microcontroller U1 starts the motor,for example, to begin the spray operation of step 104 of FIG. 3. Tostart the motor, the microcontroller U1 provides a signal to its MTRCOMMON output and its CW output. The signal at the CW output operates toturn on the triac Q241, thereby connecting the clockwise start winding19 c to motor neutral. The signal at the MTR COMMON output causes therelay contacts 206 to connect the windings 19 a and 19 c of the motor 16a to a common power connection. As a result, the run winding 19 a andthe clockwise start winding 19 c of the motor 16 a are energized and themotor 16 a begins to rotate in the clockwise direction. As the motor 16a begins to approach its steady state speed, the magnitude of thecurrent in the run winding 19 a (and clockwise start winding 19 c) willbegin to decrease. Thus, the magnitude of the signal at the ISENSE inputof the microcontroller U1 also decreases. When the magnitude of thesignal at the ISENSE input falls below a predetermined level, themicrocontroller U1 removes the signal from the CW output. As a result,the triac Q241 is turned off and the clockwise start winding 19 c isopen-circuited. The predetermined level of ISENSE is a level thatcorresponds to a run winding current consistent with the motor runningat or near steady state. At steady state, the motor no longer requiresthe start winding to be energized. Those of ordinary skill in the artmay readily determine the appropriate run winding current level at whichto turn off the start winding current.

The motor 16 a continues to run at steady state with current only in therun winding 19 a. When the microcontroller U1 stops the motor 16 a, asin the completion of step 108, then the microcontroller U1 removes thesignal from its MTR COMMON output. Removal of the signal from the MTRCOMMON output causes the motor relay coil 204 to open the motor relaycontacts 206, thereby de-energizing the run winding 19 b.

The microcontroller U1 may also cause counterclockwise operation of themotor 16 a, which may be used to during the water drainage steps 110 and116 of FIG. 3, by performing the same operations as described aboveusing its CCW output instead of the CW output.

It will be appreciated that the current sensor 220 preferably has a highdegree of accuracy (i.e. tight tolerance on resistance value). In somecases, the degree of accuracy cannot be easily achieved in a lowresistance resistor formed as a trace on a circuit board such as thatshown by example in FIG. 10. Even relatively small error in theresistance value of the current sensor (e.g. 0.049 ohms instead of 0.045ohms) can lead to unpredictability in the control operations of themicrocontroller U1. For example, consider a situation in which themicrocontroller U1 ideally causes current to be removed from a startwinding when the run winding current is N amps, and the nominal (ideal)resistance of the current sensor 220 is 0.045 volts. In such a situationthe microcontroller U1 is programmed to cause the start winding currentto be removed when the voltage drop over the current sensor 220 isN/0.045. As a result, the microcontroller U1 will cause current to beremoved from the start winding when the voltage at the measurement point228 is detected to be N/0.045 volts with respect to motor neutral. If,however, the actual resistance of the current sensor 220 is 0.049 ohms,then the run winding current will be N when the voltage at themeasurement point 228 is N/0.049 volts, not N/0.045. Nevertheless, themicrocontroller U1 would cause the current to be removed from the startwinding when the voltage at the measurement point 228 is N/0.045 volts.When the voltage at the measurement point 228 is N/0.045 volts, theactual current magnitude is higher than N due to the error in thecurrent sensor. Thus, the microcontroller U1 would turn off the startwinding current before the desired time.

To avoid such unpredictability in operation, the microcontroller U1 maybe configured to compensate for error (variation of the resistance) ofthe current sensor 220. To compensate for resistance error, themicrocontroller U1 digitally scales the magnitude of the signal atISENSE by the amount of the resistance error. Thus, if the actualresistance of the current sensor 220 is 0.049 ohms, then themicrocontroller U1 would scale the ISENSE signal by 0.045/0.049. Thus,instead of removing the current at N/0.045, current is removed at(0.045/0.049)*N/0.045, or N/0.049. As discussed above, if the actualresistance of the current sensor 220 is 0.049 ohms, then the current isN when the voltage magnitude at the measurement point 228 is N/0.049.

The percentage of resistance error may be determined any time after theetched current sensor 220 is formed, even before the primary PCB 62 ispopulated. The compensation factor derived from the determined error maythen be stored in the EEPROM U5 (see FIG. 7) or other non-volatilememory (see generally the memory 26 of FIG. 2). By providing aprogrammable memory in which to store the compensation factor, thevariable nature of the error arising from the use of an etched resistoris accommodated. In particular, because the resistance value isrelatively low (i.e. less than one-tenth of an ohm), even smallvariations in the trace thickness, geometry or width can significantlyalter the resistance value. Thus, the resistance error can vary as afunction of manufacturing tolerances, thereby requiring customcompensation in each device. The use of a programmable memory device forstoring the compensation factor allows for custom calibration of eachdevice.

Nevertheless, if manufacturing tolerances are tightened sufficiently toeliminate the need for compensation, then the requirement of using acompensation factor can be eliminated altogether.

The actuator circuit 18 includes a valve actuator circuit 230 and adetergent/rinse aid actuator circuit 232. The valve actuator circuit 230includes a semiconductor switch Q250 that gates the water valvesolenoid, not shown, to AC neutral. A VALVE CNTL output of themicrocontroller U1 is connected to the control input of the switch Q250.The detergent/rinse aid actuator circuit 232 is similarly controlledthrough a triac Q260. In the exemplary embodiment disclosed herein, thedetergent dispenser release mechanism is coupled through a first diodeD260 and the rinse-aid dispenser is coupled through a second diode D261.The second diode D261 is reverse biased with respect to the first diodeD260. So configured, if the microcontroller U1 only energizes the triacQ260 during positive half cycles of the line voltage, then only therinse aid dispenser is actuated. Similarly, if the microcontroller U1only energizes the triac Q260 during negative half cycles of the linevoltage, then only the detergent dispenser is actuated. In this manner,two separate devices may be independently controlled using a singlemicrocontroller output and a single semiconductor switch.

FIG. 9A shows a schematic diagram of the portion of the exemplarycontrol circuit that includes optical I/O circuit 14. Optical I/Ocircuit 14 includes the plurality of indicator lights 36 a through 36 iwhich in the exemplary embodiment described herein are standard lightemitting diodes (“LEDs”), such as those LEDs sold by AGILENT of PaloAlto, Calif. and designated by part number HLMP3301. Optical I/O circuit14 may also further include optical detector 37 in the form of adetector LED, such as those sold by Fairchild Semiconductor of SouthPortland, Me. and designated by part number MV-8111.

In general, indicator lights 36 a through 36 i are operably connected tomicrocontroller U1. Microcontroller U1 controllably energizes indicatorlights 36 a through 36 i at select times during the operation of thedishwasher. In particular, microcontroller U1 controllably energizesindicator lights 36 a through 36 i during dishwasher operation as nowdescribed. Indicator light 36 a is energized and thus lit when and ifthe “Hi-Temp Wash” option is selected by the operator (see FIG. 3).Microcontroller U1 similarly energizes indicator light 36 b when and ifthe “Air Dry” option is selected by the operator (see FIG. 3).Microcontroller U1 likewise energizes indicator light 36 c when and ifthe “2 Hour Delay” option is selected by the operator (see FIG. 3).Microcontroller U1 controllably energizes the indicator light 36 d whenand if the “4 Hour Delay” option is selected by the operator (see FIG.3). Microcontroller U1 further controllably energizes indicator lights36 e through 36 i that correspond to the indicia located adjacent to thelights 36 e through 36 i during operation of dishwasher 50 (see FIG. 3).

In the exemplary embodiment depicted in FIG. 9A, indicator lights 36 athrough 36 i are coupled to the A1 to A5 outputs as well as the L1 andL2 outputs of microcontroller U1. A first LED driver transistor Q1 iscoupled between a microcontroller output L1 and the anodes of eachindicator light 36 a through 36 e. A second LED driver transistor Q2 iscoupled between a microcontroller output L2 and the anodes of eachindicator light 36 f through 36 i. The cathodes of indicator lights 36 aand 36 f are coupled through a 220 ohm resistor R18 to an A1 output ofmicrocontroller U1. The cathodes of indicator lights 36 b and 36 g arecoupled through a 220 ohm resistor R47 to an A2 output ofmicrocontroller U1. The cathodes of indicator lights 36 c and 36 h arecoupled through a 220 ohm resistor R45 to an A3 output ofmicrocontroller U1. The cathodes of indicator lights 36 d and 36 i arecoupled through a 220 ohm resistor R6 to an A4 output of microcontrollerU1. The cathode of indicator light 36 e is coupled through a 220 ohmresistor R36 to an A5 output of microcontroller U1. Accordingly, themicrocontroller energizes each indicator light 36 x by providing anoutput signal on a unique combination of either L1 or L2 and one of A1,A2, A3, A4 and A5. For example, to energize indicator light 36 h, themicrocontroller controls both L2 and A3.

In accordance with one aspect of the present invention, optical I/Ocircuit 14 may control one or more of indicator lights 36 a to 36 i asan optical communication device to effectuate communication betweenmicrocontroller U1 and an external diagnostic tool. Use of one or moreof the indicator lights as both an indicator light and an opticalcommunication device reduces the need for adding an optical component tofunction as an optical communication device.

In the exemplary embodiment shown in FIG. 9A, indicator light 36 i iscontrolled to operate as an optical transmitter as well as an indicatorlight as described above. An optical detector 37, FIG. 9B, may be addedto optical circuit 14 to operate as an optical receiver but does notoperate as an indicator light. However, one of the indicator lights 36 ato 36 i may be operated as an optical receiver by modifying thecircuitry associated with the selected indicator light. To simplify thedescription of this implementation, indicator light 36 j is shownconfigured for operation as an optical receiver in FIG. 9A. To enablethis implementation, indicator light 36 j also requires access to thesurface of control panel 52 as the other indicator lights have as shownin FIG. 4. As shown in FIG. 9A, indicator light 36 j has its anodecoupled to the emitter of transistor Q2 and its cathode coupled tomicrocontroller output A5 through resistor R36. A voltage dividercomprised of R40 and R42 is coupled across indicator light 36 j and theintermediate node of the divider is coupled to the base of transistorQ4. The emitter of Q4 is coupled to the cathode of indicator light 36 jand one end of resistor R42 while the collector of Q4 is coupled toground through resistor R3. When dishwasher 50 is not operating as adishwasher, microcontroller U1 holds L2 at a high impedance state whileoutput A5 is held at a negative bias so a light pulse impinging onindicator light 36 j causes a voltage drop to occur across indicatorlight 36 j. The resulting voltage is presented at the base of transistorQ4 to forward bias the transistor so ground is coupled through R3 and Q4to the negative potential on output A5. Thus, the voltage on the RX pinof microcontroller U1 drops to indicate the light pulse of the opticalsignal. The absence of a light pulse causes the signal at the RX pin toreturn to ground. Consequently, the configuration of indicator light 36j with Q4, R40, R42, and R3 enables indicator light 36 j to operate asan optical receiver when microcontroller U1 holds output A5 at anegative potential.

As discussed above in connection with FIG. 4, indicator light 36 i islocated adjacent optical detector 37. This placement of the componentsthat may be operated as an optical transmitter and optical receiver inproximity to one another enables the communication probe, described inmore detail below, to be designed with a more compact housing for itsoptical transmitter and receiver. In an embodiment of the presentinvention, two indicator lights may be selected to be operated as anoptical transmitter and an optical receiver. Preferably, the twoselected indicator lights are located in different groups of indicatorlights 36 a to 36 i. That is, one indicator light selected to be anoptical communication device, such as an optical transmitter, may belocated in the group of indicator lights 36 a to 36 e coupled tomicrocontroller U1 through communication control component, transistorQ1, and another indicator light selected for operation as an opticalcommunication device, such as an optical receiver, may be located in thegroup of indicator lights 36 f to 36 j coupled to microcontroller U1through common control component, transistor Q2. This arrangementenables microcontroller U1 to operate independently the two selectedindicator lights. Preferably, the two indicator lights selected foroperation as optical communication devices are also located in proximityto one another to enable the communication probe to be designed morecompactly. Thus, for example, indicator light 36 b is preferably pairedwith 36 f or 36 g (FIG. 4) for operation as an optical transmitter andreceiver pair while indicator light 36 c is preferably paired with 36 gor 36 h for operation as an optical transmitter and receiver pair.

If one of the indicator lights is not configured as an optical receiver,then an optical detector may be separately provided as an opticalreceiver. An optical detector 37 may be configured and coupled tomicrocontroller U1 as shown in FIG. 9B to operate as an opticalreceiver. As shown in that figure, optical detector 37 is coupledthrough a transistor Q3 to an RX input of microcontroller U1. Inparticular, the anode of optical detector 37 is connected to the base oftransistor Q3, which is an NPN bipolar junction transistor, and thecathode of optical detector 37 is coupled to a bias voltage supply(−5V). The emitter of transistor Q3 is also coupled to the bias voltagesupply (−5V). A 220 k-ohm bias resistor R2 is coupled between the biasvoltage supply and the base of transistor Q3 while the collector oftransistor Q3 is coupled to ground through a 47 k-ohm bias resistor R3.The RX input of microcontroller U1 is coupled to the collector of thetransistor Q3 to receive an electrical signal that corresponds to theoptical signal stimulating optical detector 37. In the exemplaryembodiment described herein, indicator lights 36 a through 36 i, opticaldetector 37, resistor R2 and transistor Q3 are disposed on secondary PCB64. All other elements are disposed on primary PCB 62. (FIG. 5).

In operation, indicator light 36 i may function as an opticaltransmitter and the optical detector 37 may function as an opticalreceiver. For transmission of data signals, microcontroller U1 providescontrol signals at its L2 and A4 output to transmit data.Microcontroller U1 may negatively bias indicator light 36 i by applyinga negative potential to the cathode through the A4 output and then drivethe base of transistor Q2 with a serial data signal to transmit a datastream through indicator light 36 i operating as an optical transmitter.Alternatively, microcontroller may hold L2 at ground and thenselectively bias the cathode of indicator light 36 i with a data signalon A4 to transmit a data stream through indicator light 36 i operatingas an optical transmitter. Either method of operation enables indicatorlight 36 i to respond to a data signal and generate a correspondingoptical signal that may be received by an optical receiver so controlpanel 52 of dishwasher 50 communicates data to an optical externalreceiver of the appliance.

For reception of data signals from an external transmitter, opticaldetector 37, FIG. 9B, is selectively stimulated by light/optical signalsfrom an external optical transmitter. A light pulse in the opticalsignal causes optical detector 37 to be forward biased so a voltage ispresented at the base of transistor Q3 that provides a forward bias onthe base/emitter leg of transistor Q3. When the base/emitter leg isforward biased then the collector of transistor Q3 is coupled to thenegative bias supply coupled to the emitter and the voltage at RX dropssignificantly. Thus, an electrical signal corresponding to the opticalsignal impinging on optical detector 37 is produced on the RX input ofmicrocontroller U1 so microcontroller U1 may receive a data message froman external source.

Operating indicator light 36 i and optical detector 37 as opticalcommunication devices enables an appliance, such as dishwasher 50, tocommunicate with an external device. Preferably, the external processingdevice is a diagnostics tool that includes one or more digitalprocessing circuits. The diagnostics tool may receive diagnostic orother information from microcontroller U1 through indicator light 36 i.Data messages may be sent from the diagnostic tool to the appliancethrough optical detector 37 or one of the other indicator lightsconfigured to operate as an optical receiver as shown in FIG. 9A.

In some appliances, vacuum fluorescent displays (VFD) are used toprovide indications of the operations of an appliance rather thanindicia and indicator lights. A VFD, as shown in FIG. 10, typicallyincludes a glass substrate 232 on which semiconductor circuits, such ascircuit 234, and a plurality of phosphor pixels 236 are laid. Glasssubstrate 232 may be covered with a dark layer 238 to provide contrastto excited pixels for better visibility of the character displayed withpixels 236 on circuit 232. A plurality of semiconductor circuits isdriven to selectively energize the phosphor pixels and generatecharacters to display data regarding the operation of the appliance.However, the phosphor pixels may not produce adequate light for opticalcommunication or the processing overhead for controlling one or morepixels as low intensity optical transmitters and receivers may be tooresource intensive for implementation.

In order to provide an optical interface in an appliance that uses aVFD, a LED or other indicator light may be mounted behind the display.As long as the display background is optically transmissive, a lightmounted behind the display may be controlled to generate an opticalsignal containing appliance data and an optical detector may receive anoptical signal from an external device, such as an optical probe,through the display. If the display has a background that blocks orseverely attenuates optical signals, an aperture 242 may be provided inthe vacuum fluorescent display, preferably through the dark background,so it is aligned with an indicator light mounted behind the VFD.Preferably, two apertures 242 are formed in the VFD and two indicatorlights are mounted behind the VFD so the appliance may operate the twoindicator lights as an optical transmitter and an optical receiver. Mostpreferably, the two apertures are formed at a location that hassufficient spatial separation from one another to reduce the likelihoodof reflected light causing optical noise yet they are sufficiently closeto one another that the communication probe housing remains compact.

As shown in FIG. 10, a first aperture 242 a is located on one side ofsemiconductor circuit 234 and a second aperture 242 b is located on theopposite side of semiconductor circuit 234. Apertures 242 a and 242 bmay be etched or otherwise formed in a dark background 238 when thedisplay is manufactured. Apertures 242 a and 242 b are located so eachone aligns with a LED or other indicator light mounted behind thedisplay. When the LEDs are configured as described above, one may beoperated to transmit a light signal that passes through aperture 242 a,for example, so it may be received by an optical receiver of acommunication probe. Likewise, the other indicator light may be operatedas an optical receiver so a light signal may be received throughaperture 242 b. The optical receiver may also be implemented with anoptical detector or phototransistor mounted underneath the display inalignment with one of the apertures. When configured as described above,the optical detector or phototransistor responds as an optical receiver.

By providing an aperture 242 a, 242 b in the dark background 238 of aVFD 230 so an optical transmitter and receiver may be aligned with afirst and a second indicator light mounted behind the display, anoptical interface is provided for an appliance that uses a VFD ratherthan indicator lights and indicia for the display of operational data.When the VFD includes a dark layer and the apertures are formed withinthe dark layer, reflected light that is not substantially aligned withone of the apertures is absorbed by the dark material surrounding theapertures. Consequently, the indicator lights being operated as anoptical transmitter and an optical receiver are less prone to opticalnoise arising from reflected light. This is also the case to some extentwhen the indicator lights are located behind a VFD that does not have adark layer because the VFD is typically darker than the surface of theappliance control panel outside the region in which the display ismounted.

FIG. 11 shows an exemplary arrangement in which an exemplary diagnostictool 240 in the form of a handheld computer is configured to obtaininformation from microcontroller U1 through indicator light 36 i andoptical detector 37 located on central panel 52 when they are operatedas an optical transmitter and receiver, respectively. While diagnosticstool 240 is shown as a handheld computer or personal digital assistant,diagnostic tool 240 may be any other type of portable computer. Also,diagnostic tool 240 may be a stationary computer located, for example,at the end of an appliance assembly line for the purpose of verifyingappliances through an optical interface before shipping the appliance toretail outlets.

As shown in FIG. 11, diagnostic tool 240 is electrically coupled byelectrical cable 244 to a communication probe 246. Communication probe246 is configured for optical communication with dishwasher 50.Specifically, communication probe 246 includes an optical transmitterand an optical receiver that are spaced apart at a distance thatapproximates the distance between optical detector 37 and indicatorlight 36 i. The optical transmitter and optical receiver ofcommunication probe 246 are arranged so when the optical transmitter isaligned with optical detector 37, then the optical receiver of probe 246is aligned with indicator 36 i. Electronics are also provided incommunication probe 246 so an optical signal received from indicatorlight 36 i of dishwasher 50 is converted into an electrical data signaland returned via cable 244 to diagnostic tool 240 for processing.Diagnostic tool 240 may send data messages to dishwasher 50 by sending adata signal via cable 244 to probe 246 where it is converted into anoptical signal by the optical transmitter of probe 246. The opticalsignal transmitted from the optical transmitter of probe 246 may bereceived by optical detector 37 of dishwasher 50 and the correspondingelectrical signal received on the RX input of microcontroller U1 forprocessing. Thus, a low intensity optical interface to dishwasher 50 isobtained from the use of one or more indicator lights already availableon an appliance such as dishwasher 50. Because the indicator lights ofan appliance are relatively low intensity, communication probe 246 needsto be located closely to control panel 52 of dishwasher 50. The spatialrelationships of the optical transmitter and receiver of probe 246 andthe indicator light 36 i and optical detector 37 are discussed in moredetail below.

While the exemplary embodiment of the present invention shown in FIG. 11depicts a cable 244 coupling probe 246 to diagnostic tool 240, probe 246may be coupled directly to diagnostic tool 240 or incorporated withinthe housing of diagnostic tool 240. In this arrangement, tool 240 isbrought into proximity of indicator light 36 i and optical detector 37for communication with dishwasher 50 through control panel 52. However,this arrangement requires either the user to hold diagnostic tool 240 inalignment with indicator 36 i and optical detector 37 or couplers 268require strengthening to secure diagnostic tool 240 to control panel 52.Thus, the use of cable 244 to couple probe 246 to diagnostic tool 240 ispreferred.

FIG. 12 shows an exploded view of an exemplary embodiment ofcommunication probe 246 in further detail. Communication probe 246includes a housing formed by a back member 248 and a front member 254 toprovide an interior 256. Communication probe 246 further includes anoptical receiver 250 and an optical transmitter 252 mounted on support258 for placement within the housing. Support 258 may be a printedcircuit board that is secured within interior 256. Front member 254includes apertures 260 and 262 that align with receiver 250 andtransmitter 252 when the housing is assembled so the receiver 250 andtransmitter 252 may optically communicate with elements external to thehousing. Apertures 260 and 262 may be completely open or they mayinclude a substantially transparent (or otherwise opticallytransmissive) element, such as a lens.

Communication probe 246 further includes an electronics module 265containing electronics for driving optical transmitter 252 in accordancewith data signals received from diagnostic tool 240 and for transmittingsignals received by optical receiver 250 to diagnostic tool 240. Theelectronic components of module 265 may be attached to andelectronically coupled together via a printed circuit on support 258.Electronics module 265 may include a connector 266 for receivingconnector 264 of cable 244 to couple the conductors within cable 244 tothe electronics within module 265. Connector 266 also couples theelectronics of module 265 to supply voltage signals from diagnosticstool 240. Preferably, a RS-232 integrated circuit in module 265 convertsthe voltage supply signals received from diagnostic tool 240 to voltagelevels appropriate for use within a preferred embodiment of probe 246.In the exemplary embodiment shown in FIG. 12, connectors 264 and 266 areRS-232 connectors having nine pins each. However, other pin arrangementsand numbers of pins may be used. Of course, other electricalspecifications and connector arrangements may be used without departingfrom the principles of the present invention.

Probe 246 may be provided with housing couplers 268 for removablysecuring probe 246 to control panel 52 for optical communication betweenreceiver 250 and transmitter 252 of probe 246 and indicator light 36 iand optical detector 37 of dishwasher 50 when they are operated as anoptical transmitter and receiver as discussed above. Couplers 268 may beone or more suction cups for engaging the surface of control panel 52 orthey may be one or more magnets provided control panel 52 is comprisedof a material such as sheet metal that is attracted to magnets.

In operation, a user aligns optical transmitter 252 and optical receiver250 of probe 246 with indicator light 36 i and optical detector 37,respectively. The probe is advanced toward control panel 52 untilcouplers 268 engage panel 52 and communication probe 246 is secured tothe panel so optical receiver 250 and transmitter 252 are aligned withand in close proximity to indicator light 36 i and optical detector 37,respectively, for the optical communication of data between diagnostictool 240 and dishwasher 50. If some misalignment occurs, the user mayslide probe 246 in any direction along the control panel 52 untildiagnostic tool 240 and the microcontroller U1 establish communications,signifying that optical receiver 250 and transmitter 252 aresufficiently aligned with indicator light 36 i and optical detector 37for communication.

Other types of couplers may also be used to secure probe 246 inproximity to control panel 52. For example, mechanical mounts may bedisposed on probe 246 to cooperate with mechanical features ofdishwasher frame 51 to align the optical transmitter and receiver ofprobe 246 with indicator light 36 i and optical detector 37 of controlpanel 52. Indeed, the shape of probe 246 may be used to couple probe 246to panel 52 if corresponding alignment supports are disposed ondishwasher control panel 52. However, the use of magnets or suction cupsprovides the added advantage of not requiring any special mechanicalmodifications to existing appliance panels.

FIGS. 13 and 14 show exemplary flow diagrams of operations carried outin a typical communication operation between diagnostic tool 240 andmicrocontroller U1. FIG. 13 shows the operations of diagnostic tool 240during communication with an appliance and FIG. 14 shows thecorresponding operations of microcontroller U1 during communication witha diagnostic tool 240.

Referring to FIG. 13, diagnostic tool 240 may begin communicationoperations by generating a handshake or “wake-up” message or signalpattern on a free-run, repeating basis (block 302). The “wake-up”message is repeated until an acknowledgement message or signal isreceived by diagnostic tool 240 from the appliance with which tool 240is communicating (block 304). In response to receipt of theacknowledgement message, diagnostic tool 240 preferably provides avisible or audible signal confirming to a human operator thatcommunications with the appliance control circuit have been established.This confirmation signal may be used to assist a technician in aligningthe optical transmitter and receiver of communication probe 246 withindicator light 36 i and optical detector 37 on control panel 52. Thetechnician stops moving probe 246 once the visible or audible indicationis received (block 304).

Thereafter diagnostic tool 240 formulates a data request message (block306). In particular, diagnostic tool 240 may form a data message thatrequests a specific type of data from microcontroller U1. As discussedfurther below, microcontroller U1 may be configured to store a varietyof diagnostic or operational statistics and data. Accordingly,diagnostic tool 240 may request a particular subset of the data storedby microcontroller U1. Diagnostic tool 240 may employ any number ofmechanisms to allow a user to specify the types of data to be retrievedfrom dishwasher control circuit 10. In an alternative embodiment, thetype of data retrieved from microcontroller U1 may be predetermined,thereby potentially eliminating the need for formulation of a datarequest message.

The method continues with diagnostic tool 240 receiving data frommicrocontroller U1 in response to the transmission of a data requestmessage and determining whether the received data are valid (Block 308).To this end, diagnostic tool 240 checks for data integrity using any ofa plurality of known methods and also determines whether the receivedinformation is in the correct data protocol. If valid data are notreceived, then diagnostic tool 240 may formulate another request (block306) and retransmit the data request message. If, however, validresponsive data are received, then diagnostic tool 240 may store, printand/or display information based on the received data (block 310).Diagnostic tool 240 may further process the data prior to displaying orprinting or it may display or print the retrieved data directly.

Diagnostic tool 240 may determine whether any additional data are to berequested from dishwasher control circuit 10 (Block 312). For example,diagnostic tool 240 may query the technician or operator via a screendisplay as to whether additional data are to be requested (block 306).If additional data are to be requested, then diagnostic tool 240 maygenerate another data request message (block 306). Otherwise, diagnostictool 240 has completed the communication operation. Further processing,displaying and printing of the retrieved data or information derivedtherefrom may be accomplished after the communication operations havebeen completed.

FIG. 14 shows the operations of microcontroller U1 that may be performedin conjunction with the communication operation described in FIG. 13.Microcontroller U1 may periodically scan the RX input for the handshakeor “wake-up” signal generated by diagnostic tool 240 (block 322). Suchperiodic scanning may occur during dishwasher operations using typicalinterrupt or polling processing. Because the operation of dishwasher 50is typically not computationally intensive, periodic scanning may bereadily carried out several times per second without degrading theperformance of the dishwashing operations described above in connectionwith FIG. 3. Microcontroller U1 determines if a handshake or “wake-up”signal has been detected (block 324) and if microcontroller U1 does notrecognize a handshake message then microcontroller U1 continues itsperiodic scanning (block 322) until a handshake signal is detected.

When microcontroller U1 does recognize an appropriate handshake or“wake-up” signal (block 324), then microcontroller U1 transmits anacknowledgement message to diagnostic tool 240 using indicator light 36i (block 326). Microcontroller U1 then receives a data request messagegenerated by diagnostic tool 240 via optical detector 37 and parses themessage to determine the type of data being requested by diagnostic tool240 (Block 328). The requested diagnostic data may be stored locallywithin microcontroller U1 or in EEPROM U5. The diagnostic data typicallycommunicated from dishwasher 50 include data gathered and stored duringoperation of the dishwasher 50. Such data may include statistics orinformation regarding detected out-of-boundary conditions. For example,microcontroller U1 may record an out-of-boundary event if thetemperature sensor reaches a certain temperature or if the temperaturefails to reach a particular temperature. Other diagnostic data mayinclude a count of the number of cycles run by the machine, the numberof hours motor 16 a has operated, or similar usage information. Theexact nature of the type of diagnostic information obtained, and themanner in which it is stored, varies based on the needs and strategiesof a particular implementation.

Microcontroller U1 retrieves the requested data from the memory (e.g.,internal memory or EEPROM U5) and, if necessary, processes the raw datato obtain the type of data requested (block 330). Microcontroller U1transmits the retrieved data to diagnostic tool 240 via indicator light36 i (Block 332). To this end, microcontroller U1 configures theresponsive data message to the format expected by diagnostic tool 240.

Microcontroller U1 determines whether any further data request signalsare generated (block 334). If no such new requests are received before atime-out period, then microcontroller U1 continues to periodicallymonitor for a handshake or “wake-up” signal (block 322). If anadditional request is received, then microcontroller U1 receives andimplements the data request (block 328). Alternatively, microcontrollerU1 may return directly to scanning for handshake signals (block 322)without checking for an additional data request message (block 334). Inthis implementation of the method, additional requests are handled inthe same manner as the original data request.

A system and method for implementing the management of the communicationbetween probe 246 and an appliance through an optical interface aredisclosed in co-pending patent application entitled System and Methodfor Communicating with an Appliance Through an Optical Interface Using aControl Panel Indicator and having Ser. No. 10/348,305 that was filed onJun. 24, 2003. That application is owned by the assignee of the presentapplication and is hereby expressly incorporated in its entirety byreference.

One exemplary embodiment of power and data couplings between diagnostictool 240 and communication probe 246 is shown in FIG. 15. Diagnostictool 240 is shown to be a handheld computer that includes a power supply278, a microprocessor 270 and communication interface 272. Of course,diagnostic tool 240 may have other electronics including, but notlimited to, display drivers, memory and user interface electronics.Interface 272 couples power conductors 274 of cable 244 to power supply278 and couples data conductors 276 of cable 244 to microprocessor 270.The number of power conductors 274 and data conductors 276 may differfrom the number of power and data conductors shown in FIG. 15.

Preferably, communication interface 272 is an RS-232 interface availablein most handheld computers, such as a Palm Pilot personal digitalassistant. However, interface 272 may be any type of communicationinterface that typically generates reference voltage signals fortransmission over power conductors 274 of cable 244. With reference toFIG. 15, connector 266 receives the reference voltage signals on powerconductors 274 and delivers them to power supply 280 for use withinprobe 246. Power supply 280 distributes the reference voltage signalswithin probe 246 for powering components and may include a voltageconverter for converting, if necessary, the reference voltage signalsinto other voltage levels appropriate for powering the electronicswithin probe 246. Preferably, power supply 280 includes an RS-232interface integrated circuit that generates the RS-232 reference voltagesignals of +12V and −12V from the reference voltage signals of +5V andground (GRND). These voltage signals may be used by the electronicswithin probe 246, for example, to power communication driver 282.Communication driver 282 generates an electrical data signalcorresponding to the optical signal stimulating optical receiver 250 fortransmission to diagnostic tool 240 through one or more of theconductors 276. Communication driver 282 also provides the data signalreceived from diagnostic tool 240 to optical transmitter 252 fortransmission to indicator light 36 i.

FIG. 16A shows an embodiment in which a −12V reference voltage signal isapplied to optical receiver 250. Optical receiver 250 may be comprisedof a phototransistor 288 and an amplifier network that includesamplifiers A1 and A2. Preferably, amplifiers A1 and A2 are high speedoperational amplifiers. Resistor R284 is coupled between the emitter ofphototransistor 288 and ground so a signal voltage is provided to one ofthe inputs of amplifier A1 when light impinges on phototransistor 288and causes it to conduct current from its collector to its emitter.Resistors 302 and 303 set the gain for amplifier A1 in a known manner,Preferably, the gain for amplifier A1 is set to thirteen (13). AmplifierA2 is operated as a comparator. A voltage divider comprised of R301 andR300 provide a reference voltage at the node shared by the resistors.This reference voltage, which is preferably 0.63 volts, is provided tothe one of the inputs for amplifier A2 while the output of amplifier A1is supplied to the other input of amplifier A2 through an input resistorR306. The output of amplifier A2 is rectified by resistor 308 and diodeD1 to provide an electrical signal at node 290 that corresponds to thelight signal impinging on phototransistor 288. Preferably, the −12Vvoltage from the RS-232 converter and the +5V voltage are provided tooperational amplifiers A1 and A2 as operating voltages for the amplifiernetwork. By using the −12V signal from RS-232 converter rather than theelectrical ground signal supplied through the cable, the operationalamplifiers A1 and A2 are operated in a high speed mode. Thus, theinclusion of the RS-232 converter in communication probe 246 improvesthe response of the optical receiver 250. The maximum baud rate for theimproved optical receiver is 56K baud.

FIG. 16B depicts an exemplary construction of optical transmitter 252comprised of a NPN transistor 292, a LED 294, and two resistors R286 andR288. Resistor R286 is coupled between the collector of transistor 292and the base of transistor 292. LED 294 and resistor R288 are coupled inseries between the emitter of transistor 292 and ground. A data signalprovided from diagnostic tool 240 through cable 244 to communicationdriver 282 is supplied to the base of transistor 294. When the datasignal has a logical high value, the base/emitter leg of transistor 294is forward biased and the +5V power supply is coupled from the collectorto electrical ground through LED 294 and resistor 288 so LED 294 isstimulated to generate light. Otherwise, the data signal does not turnon transistor 292 and LED 294 remains off. In this manner, an electricaldata signal may be used to generate a corresponding light signal.

In one embodiment of the present invention, LED 294 is the same type ofLED as indicator light 36 i and phototransistor 288 is the same type ofoptical detector as optical detector 37. Preferably, either LED 294 is ahigh intensity LED that generates light that is more intense than thelight from indicator light 36 i or phototransistor 288 is a sensitivephototransistor that responds to light more quickly than opticaldetector 37. Most preferably, LED 294 is a high intensity LED andphototransistor 288 is a sensitive phototransistor. The use ofcomponents in probe 246 that are different than those in dishwasher 50enhances the effectiveness of communication between dishwasher 50 andprobe 246 without requiring modification to dishwasher 50. Furthermore,this reduces the likelihood that optical detector 37 is stimulated bystray light signals from the ambient environment. Optical detector 37may be especially vulnerable to stray light signals while control panel52 is not engaged to the probe 246 and optical detector 37 is uncovered.By making the optical transmitter of probe 246 more intense rather thanmaking optical detector 37 more sensitive, optical communication isimproved without making the appliance more sensitive to light signalswhen the appliance is not in its communication mode.

Preferably, a high intensity LED 294 is one that generates light pulsesat a brightness level approximately between 8000 millicandelas and31,000 millicandelas at 20 ma through the LED. A standard LED, such asthat used for indicator lights 36 a-36 i, typically generate light inthe range of 4 to 7 millicandelas. Preferably, a sensitivephototransistor is one that generates a collector photo current of 5 to15 mA in response to a light pulse of 100 lx. On the other hand, anoptical detector, such as optical detector 37, generates 50 to 100 μAwhen stimulated by a light pulse of 1 mW/cm². As noted above, a standardLED may also be used as an optical receiver. When a LED is configured tobe an optical receiver, the LED is estimated to generate a current of 50to 100 μA in response to a light pulse that of 1 mW/cm². A highintensity LED is available from Agilent of Palo Alto, Calif. anddesignated by part number HLMP-EG08-Y2000. A sensitive phototransistoris available from Panasonic of Secaucus, N.J. and designated by partnumber PNZ-108. This type of sensitive phototransistor generatessufficient current to generate an electrical data signal in response tolight in a range as low as approximately 10 lx to 30 lx.

FIG. 17 illustrates communication probe 246 being engaged with controlpanel 52 for bi-directional optical communication between diagnostictool 240 and dishwasher 50. In FIG. 17, indicator light 36 i issubstantially aligned with optical receiver 250 of probe 246 and opticaldetector 37 is substantially aligned with optical transmitter 252.Preferably, distance d5 shown in FIG. 17 is no more than 20 mm as thatis approximately the maximum distance that a standard LED, such asindicator light 36 i, is able to effectively transmit a light signal.Distances d6 and d7 are approximately the same so optical transmitter252 may be aligned with optical detector 37 while optical receiver 250is also aligned with indicator light 36 i. This distance is preferablyno less than 12 mm to reduce the likelihood of cross-talk between thetwo aligned optical communication paths shown in FIG. 17. Preferably,distance d7 in probe 246 is designed to accommodate the spatialseparation of the indicator light and optical detector pair or indicatorlight pair selected to be operated as an optical transmitter andreceiver at the appliance. Probe 246 may be secured to control panel 52via couplers 268 as discussed above in connection with FIGS. 11 and 12.

The optical signal transmitted from indicator light 36 i to opticalreceiver 250 may have the same or opposite logical polarity as theoptical signal transmitted from optical transmitter 252 to opticaldetector 37. That is, both optical transmitter 252 and indicator light36 i may have the same logical polarity by transmitting a light pulse torepresent a logical ‘1’ or both may be turned off to represent a logical‘1’ when probe 246 is coupled to dishwasher 50 for communication.Preferably, however, indicator light 36 i and optical transmitter 252transmit light signals having opposite logical polarity by havingindicator light 36 i transmit a light pulse to represent a logical ‘1’while optical transmitter 252 may be turned off to represent a logical‘1’ in its transmitted data stream. Alternatively, opposite logicalpolarity may be achieved by turning off indicator light 36 i torepresent a logical ‘1’ while optical transmitter 252 sends a lightpulse to represent a logical ‘1’ in its transmitted data stream. The useof optical signals having opposite logical polarity improves noiseimmunity at optical receiver 250 and optical detector 37. Mostpreferably, as shown in FIG. 18, indicator light 36 i transmits a lightpulse to represent a logical ‘0’ while optical transmitter 252 is turnedoff to represent a logical ‘0’ in its data stream. Furthermore,indicator light 36 i and optical transmitter 252 continuously transmit alogical ‘0’ when a data signal is not modulating the optical signal.

The above-described most preferred arrangement improves noise immunityat optical detector 37 and optical receiver 250 because the light fromindicator light 36 i is not as intense as the light optical transmitter252 when a high intensity LED is used for transmitter 252. Thus,reflected light is less likely to impinge upon optical detector 37 at anintensity level sufficient to stimulate optical detector 37. Likewise,optical transmitter 252 is turned off so it does not contributereflected light between probe 246 and control panel 52. When opticaltransmitter 252 does commence transmission, any reflected light arisingfrom transmission of a logical ‘1’ amplifies the logical ‘0’ value beingtransmitted by a continuous light signal from indicator light 36 i.Consequently, this logical scheme reduces the risk that reflected lightcauses the reception of erroneous signals, especially when only one ofindicator light 36 i and optical transmitter 252, is being modulated bya data signal.

In the embodiment depicted in FIG. 19, indicator light 36 i is in an ONstate while not transmitting information, i.e., no data signal ismodulating indicator light 36 i and optical transmitter 252 is in an OFFstate while not transmitting information, as is desirable to reduce theoccurrence of optical noise at the optical receiver 250. However, thisresult is not achieved by using opposite logic polarity at indicatorlight 36 i and optical transmitter 252 as was described with referenceto FIG. 18. Rather, both indicator light 36 i and optical transmitter252 generate data signals having the same logic polarity duringtransmission of data. When a modulating data signal is absent, however,indicator light 36 i is maintained in an ON state. Conversely, opticaltransmitter 252 is maintained in an OFF state when a modulating datasignal is absent. The ON state of indicator light 36 i when themodulating data signal is absent may be implemented in software, as iswell known to one of ordinary skill in the art.

In an alternative embodiment depicted in FIGS. 20 and 21, communicationprobe 246 is powered by an energy storage unit in the form of a directcurrent (DC) battery pack 350 instead of power signals from diagnostictool 240. Battery pack 350 may be coupled between diagnostic tool 240and communication probe 246 by cables 354 and 358. Battery pack 350 mayinclude a battery charger circuit 360, a battery 364, and a switch 368.Cable 354 couples data signals between diagnostic tool 240 and batterypack 350 while cable 358 couples power and data signals between batterypack 350 and communication probe 246. Switch 368 couples the power leadsof battery 364 to cable 358 so power may be delivered from battery 364to communication probe 246. A power status signal, which indicateswhether diagnostic tool 240 is in an active or sleep mode, is alsocoupled to switch 368. In response to the power status signal indicatingdiagnostic tool 240 is in sleep mode, switch 368 disconnects the powerleads of battery 364 from cable 358 so battery 364 no longer providespower to probe 246. Otherwise, switch 368 couples the power leads frombattery 364 to cable 358 for the delivery of electrical power to probe246.

Preferably, diagnostic tool 240 includes a watchdog timer thatmicrocontroller 270 keeps alive unless no user activity, such as a keydepression, occurs. When the watchdog timer expires, microcontroller 270puts diagnostic tool 240 in the sleep mode to conserve its internalbattery. The corresponding change in the power status signal causesswitch 368 to disconnect battery 364 from probe 246 as described above.Preferably, battery 364 is a lithium battery such as the onemanufactured by Panasonic of Secaucus, N.J. and designated by partnumber CGA 103450, although other battery types may be used. Preferably,battery pack 350 includes a charger circuit 360 with an externalconnector 370 for coupling charger circuit 360 to a conventional ACcurrent source. Charger circuit 360 converts AC current into anappropriate form for recharging battery 364. Of course, if disposablebatteries are used for battery 364 then charger circuit 360 is notrequired for battery pack 350.

When microcontroller 270 responds to user activity, such as depressionof a key on diagnostic tool 240, microcontroller 270 activates thewatchdog timer to put the power status signal at its active state. Inresponse, switch 368 couples battery 364 to probe 246 so the componentsof the probe are energized for communication with dishwasher 50. Whilecable 358 is shown coupling battery pack 350 to probe 246, battery pack350 may be coupled directly to probe 246. To implement direct coupling,a data bus 372 couples the data signals communicated through cable 354to the components within probe 246 and an interconnect 392 is providedbetween battery 364 and power supply 280 of probe 246. Probe 246 fitswithin the recess of battery pack 350 so interconnect 392 engagesconductors that couple the circuitry of probe 246 to battery 364 ofbattery pack 350. Switch 398 selectively couples battery 364 tointerconnect 392 in a manner similar to that previously described.Alternatively, battery pack 350 may be adapted so it may be directlycoupled to the diagnostic tool. The cable from battery pack 350 thensupplies power and communicates data signals with the communicationprobe as described above.

While the present invention has been illustrated by the description ofexemplary processes and system components, and while the variousprocesses and components have been described in considerable detail,applicant does not intend to restrict or in any limit the scope of theappended claims to such detail. Additional advantages and modificationswill also readily appear to those skilled in the art. The invention inits broadest aspects is therefore not limited to the specific details,implementations, or illustrative examples shown and described.Accordingly, departures may be made from such details without departingfrom the spirit or scope of applicant's general inventive concept.

1. An optical interface for an appliance using indicator lightscomprising: a vacuum fluorescent display; and a first indicator lightmounted behind the vacuum fluorescent display (VFD) so that the firstindicator light may be operated as an optical communication device foroptical communication through the vacuum fluorescent display.
 2. Theoptical interface of claim 1 wherein the VFD includes a dark layercovering a glass substrate and a first aperture is formed in the darklayer so that the indicator light may be aligned with the first aperturein the vacuum fluorescent display for enabling optical communicationthrough the VFD.
 3. The optical interface of claim 1 further comprising:a second indicator light mounted behind the VFD so that the secondindicator light may be operated as an optical communication device foroptical communication through the VFD.
 4. The optical interface of claim3 wherein the first indicator light is operated as an opticaltransmitter and the second indicator light is operated as an opticalreceiver.
 5. The optical interface of claim 4, the VFD furthercomprising: a dark layer covering a glass substrate; and a firstaperture and a second aperture being in the dark layer so the first andsecond indicator lights are enabled for optical communication throughthe dark layer and the dark layer absorbs light not substantiallyaligned with either the first or the second aperture.
 6. The opticalinterface of claim 2 wherein the first aperture is located approximatelyequidistant from four phosphor pixels.
 7. The optical interface of claim5 wherein the first aperture is located approximately equidistant from afirst group of four phosphor pixels and the second aperture is locatedapproximately equidistant from a second group of four phosphor pixels.8. A method for enabling optical communication with an appliance havinga vacuum fluorescent display comprising: mounting a first indicatorlight behind a vacuum fluorescent display (VFD); and operating the firstindicator light as an optical communication device for opticalcommunication through the VFD.
 9. The method of claim 8 wherein thefirst aperture formation includes: forming a first aperture in a darklayer covering a glass substrate of the vacuum fluorescent display. 10.The method of claim 8 further comprising: mounting a second indicatorlight behind the vacuum fluorescent display; and operating the secondindicator light as an optical communication device for opticalcommunication through the VFD.
 11. The method of claim 10 furthercomprising: operating the first indicator light as an opticaltransmitter; and operating the second indicator light as an opticalreceiver.
 12. The method of claim 11 further comprising: forming a firstaperture and a second aperture in a dark layer covering a glasssubstrate of the VFD so the first and second indicator lights areenabled for optical communication through the dark layer and the darklayer absorbs light not substantially aligned with either the first orthe second aperture.
 13. The method of claim 9 wherein the firstaperture formation includes: locating the first aperture approximatelyequidistantly from four phosphor pixels.
 14. The method of claim 12wherein the first aperture formation includes: locating the firstaperture approximately equidistantly from a first group of four phosphorpixels; and the second aperture formation includes: locating the secondaperture approximately equidistantly from a second group of fourphosphor pixels.
 15. An appliance enabled for optical communication witha diagnostic tool comprising: an appliance having a control panel; avacuum fluorescent display mounted in the control panel; and anindicator light mounted behind the vacuum fluorescent display foroptical communication between the indicator light and a diagnostic toolthrough the vacuum fluorescent display (VFD).
 16. The appliance of claim15 wherein the VFD includes a dark layer covering a glass substrate anda first aperture is formed in the dark layer.
 17. The appliance of claim15 further comprising: a second indicator light mounted behind thevacuum fluorescent display for optical communication through the VFD.18. The appliance of claim 17 wherein the first indicator light isoperated as an optical transmitter and the second indicator light isoperated as an optical receiver.
 19. The appliance of claim 18, thevacuum fluorescent display further comprising: a dark layer covering aglass substrate; and a first aperture and a second aperture are in thedark layer so the first and second indicator lights are enabled foroptical communication through the dark layer and the dark layer absorbslight not substantially aligned with either the first or the secondaperture.
 20. The appliance of claim 16 wherein the first aperture islocated approximately equidistant from four phosphor pixels in the VFD.